NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, P.O. Box 59, NL-1790 AB, Den Burg, The Netherlands.
School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK.
Nat Commun. 2020 Aug 7;11(1):3939. doi: 10.1038/s41467-020-17408-w.
The recently discovered DPANN archaea are a potentially deep-branching, monophyletic radiation of organisms with small cells and genomes. However, the monophyly and early emergence of the various DPANN clades and their role in life's evolution are debated. Here, we reconstructed and analysed genomes of an uncharacterized archaeal phylum (Candidatus Undinarchaeota), revealing that its members have small genomes and, while potentially being able to conserve energy through fermentation, likely depend on partner organisms for the acquisition of certain metabolites. Our phylogenomic analyses robustly place Undinarchaeota as an independent lineage between two highly supported 'DPANN' clans. Further, our analyses suggest that DPANN have exchanged core genes with their hosts, adding to the difficulty of placing DPANN in the tree of life. This pattern can be sufficiently dominant to allow identifying known symbiont-host clades based on routes of gene transfer. Together, our work provides insights into the origins and evolution of DPANN and their hosts.
最近发现的 DPANN 古菌是一个具有小细胞和基因组的潜在深分枝、单系辐射的生物体。然而，各种 DPANN 分支的单系性和早期出现及其在生命进化中的作用仍存在争议。在这里，我们重建和分析了一个未被描述的古菌门（疑似未发现古菌门）的基因组，揭示其成员具有小的基因组，虽然可能通过发酵来保存能量，但可能依赖于伙伴生物来获取某些代谢物。我们的系统发育基因组学分析强有力地将疑似未发现古菌门置于两个高度支持的“DPANN”族之间的独立谱系中。此外，我们的分析表明 DPANN 与它们的宿主交换了核心基因，这增加了将 DPANN 置于生命之树中的难度。这种模式可能非常占主导地位，足以根据基因转移的途径来识别已知的共生-宿主进化枝。总的来说，我们的工作提供了对 DPANN 及其宿主的起源和进化的深入了解。
